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Nanowire pH Sensors Experiment - Student

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* 1. Please identify the school where you performed the Nanowire pH Sensors laboratory:

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* 2. In what grade are you currently enrolled?

8th grade or younger

9th

10th

11th

12th

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* 3. After performing this hands-on activity, please rate how well you understand the following:

	Not at all	A little	Mostly	Very
A sensor converts one signal (in the nanowire pH sensor example, the chemical signal of acidity) into another type of signal readable to a person (e.g. electricity that lights the LED)	A sensor converts one signal (in the nanowire pH sensor example, the chemical signal of acidity) into another type of signal readable to a person (e.g. electricity that lights the LED) Not at all	A sensor converts one signal (in the nanowire pH sensor example, the chemical signal of acidity) into another type of signal readable to a person (e.g. electricity that lights the LED) A little	A sensor converts one signal (in the nanowire pH sensor example, the chemical signal of acidity) into another type of signal readable to a person (e.g. electricity that lights the LED) Mostly	A sensor converts one signal (in the nanowire pH sensor example, the chemical signal of acidity) into another type of signal readable to a person (e.g. electricity that lights the LED) Very
The longer the conducting wire, the higher its resistance. The wider the conducting wire, the better it conducts (i.e. lower resistance).	The longer the conducting wire, the higher its resistance. The wider the conducting wire, the better it conducts (i.e. lower resistance). Not at all	The longer the conducting wire, the higher its resistance. The wider the conducting wire, the better it conducts (i.e. lower resistance). A little	The longer the conducting wire, the higher its resistance. The wider the conducting wire, the better it conducts (i.e. lower resistance). Mostly	The longer the conducting wire, the higher its resistance. The wider the conducting wire, the better it conducts (i.e. lower resistance). Very
Lower pH solutions have more available protons for acid/base reactions, favoring the protonation processes. If pH is high, the reverse is true.	Lower pH solutions have more available protons for acid/base reactions, favoring the protonation processes. If pH is high, the reverse is true. Not at all	Lower pH solutions have more available protons for acid/base reactions, favoring the protonation processes. If pH is high, the reverse is true. A little	Lower pH solutions have more available protons for acid/base reactions, favoring the protonation processes. If pH is high, the reverse is true. Mostly	Lower pH solutions have more available protons for acid/base reactions, favoring the protonation processes. If pH is high, the reverse is true. Very

Please respond to the following questions.

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* 4. The sensing element of the sensor (the black goo) is a dense aggregated mesh of nanowires made of a polymer called polyaniline. Because the diameter of each nanowire is small (<50nm), the sensing element of nanowires is significantly more sensitive to the chemical environment than a single indivisible polyaniline film of the same thickness. Why is this the case?

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* 5. When is resistance of the polyaniline nanowire higher, when exposed to acid or to base? Why is this so?

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* 6. Why do you have to wait for the polyaniline solution to dry before testing your sensor? Consider what happens if you connect the circuit when the polyaniline is still wet.

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* 7. The nanowire pH sensor can determine whether a solution is acidic or basic because the solution gives off chemical vapor that is detectable through the air. Provide two examples of instruments you know that can detect chemicals in the air (hint: one is never far from your eyes).

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* 8. Identify any concepts that you might have better understood after performing this activity:

None

Acid/base/pH

Resistance

Polymer

Sensors

Circuit

Other (please specify)

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* 9. On a scale from 1 to 4, where 1 means "not at all" and 4 means "very much", rate the following:

	1	2	3	4
Did you find the science you learned in this activity interesting?	Did you find the science you learned in this activity interesting? 1	Did you find the science you learned in this activity interesting? 2	Did you find the science you learned in this activity interesting? 3	Did you find the science you learned in this activity interesting? 4
Do you want to learn more about how to modify material properties?	Do you want to learn more about how to modify material properties? 1	Do you want to learn more about how to modify material properties? 2	Do you want to learn more about how to modify material properties? 3	Do you want to learn more about how to modify material properties? 4
How well can you explain how to build a chemical sensor using nanomaterials to someone who doesn’t know (perhaps a younger sibling)?	How well can you explain how to build a chemical sensor using nanomaterials to someone who doesn’t know (perhaps a younger sibling)? 1	How well can you explain how to build a chemical sensor using nanomaterials to someone who doesn’t know (perhaps a younger sibling)? 2	How well can you explain how to build a chemical sensor using nanomaterials to someone who doesn’t know (perhaps a younger sibling)? 3	How well can you explain how to build a chemical sensor using nanomaterials to someone who doesn’t know (perhaps a younger sibling)? 4